The present invention pertains to a blowing device for a laser means with the features described in the preamble of the principal claim.
Such a blowing device has been known from practice. It may be associated with a laser welding means or a laser cutting means by means of a suitable bracket. The blowing device has an elongated nozzle, which is directed at right angles to the laser beam and generates a gas flow passing through the laser beam. On the underside, the nozzle has an air feed, which opens in the vicinity of the nozzle opening and via which an incoming air flow can be fed to the gas flow at an acute angle. The housing of the laser head joins on the other side of the nozzle.
Thus, an incoming air flow guided essentially in parallel is generated under the gas flow in the prior-art blowing device. An air curtain, which is to protect the laser optical system from contamination or damage by spatters flying up from the melt, shall be formed by the two flows. The prior-art arrangement has the drawback that, on the one hand, it is arranged at a great distance from the welding or cutting site, as a result of which the gas and air flows must cover and protect a relatively large cross section. This requires a very high kinetic flow energy, which can be accomplished only insufficiently because of the diffusor effect and the pressure limited to a maximum of about 2.5 bar. On the other hand, the two flows are not yet sufficiently stable to guarantee an optimal protection from spatters. Furthermore, there are noise problems and there is an unfavorable space requirement.
Another blowing device has been known from DE-A 44 35 531. A gas flow is guided here along a deflecting mirror in the laser optical system. This requires a corresponding design of the laser means. The gas flow also must be curved.
Another blowing device shown in WO 95/03911, which provide closed channel for the gas flow and has a correspondingly complicated design. As a result, the blowing device considerably reduces the freedoms of design and the fields of use of the laser means.
The object of the present invention is to show a better blowing device.
This object is accomplished by the present invention with the features described in the principal claim.
In the blowing device according to the present invention, the gas flow generated by the nozzle arrangement is enclosed and guided on both sides, as a result of which swirling and consequently flow losses are extensively avoided. The kinetic energy and the blowing-away force of the gas flow are preserved, and the outflow pressure, which is limited for physical reasons, is optimally utilized.
The guiding of the gas flow can be accomplished either by two incoming air flows converging at an acute angle or essentially in parallel or by such an incoming air flow and a parallel protective glass. This flow guiding also minimizes the noises. The blowing device has a substantially simpler design and is less expensive than prior-art embodiments. In addition, it may be positioned at any suitable point and it does not have an adverse effect on a possibly existing protective gas feed for the welding process.
In the preferred embodiment, the nozzle is arranged at an open nozzle holder and may also be fastened in a height-adjustable manner. This makes possible the lateral feed of incoming air from the environment and an outside flow around the nozzle, which is also especially advantageous for the flow guiding in conjunction with the drop or wing shape, which is favorable for flow. In addition, the gas and air flow may be placed at a favorable level, at which the scattering or cone cross section is relatively small for protection against spatters, and the existing kinetic energy of the air flow is sufficiently strong for blowing away even larger spatters. In addition, the other components of the laser means are not affected adversely due to the open design and arrangement of the blowing device.
Additional advantageous embodiments of the present invention are described in the subclaims.